This application relates to a control for a fuel pump, wherein the fuel pump motor can be stopped quickly with simple controls.
Electric motor controls are becoming more and more complex. Typically, three phases of power are supplied to a stator to drive a rotor for the electric motor. In addition, a control coil controls the operation of the motor. An inverter is provided with a gate drive, and controls the flow of the power to coils associated with the three phases.
It is known to have a buck regulator upstream of the inverter, and acting to control the voltage supply from a voltage source to the inverter.
In many applications, it becomes necessary to stop the flow of fuel under certain emergency conditions. As an example, if the motor experiences high current spikes, voltage spikes, etc., it is desirable to stop the operation of the electric motor immediately. Further, other conditions, such as a fire, fuel leakage, etc., would point to immediately stopping the electric motor. Thus, it is desirable to stop a fuel pump within a matter of milliseconds once a decision is made to stop the fuel pump.
Fuel pumps of the above sort become particularly challenging to control when mounted to provide fuel to a gas turbine engine on an aircraft. In such applications, the size and weight of the control become critical. It always desirable to decrease the weight of components associated with aircraft engines.
In the prior art, the shut off signal for the electric motor flowed through the buck regulator. Since, the power flow in the prior art is unidirectional, a transient suppressor device on a dc bus would be required to maintain voltage within specification limits during fast shutdown, when the motor operates in the regenerative mode. In addition, the prior art utilizes control winding not only as a protective device in the dual redundancy arrangement, but as a buck regulator inductor. This required that the size and weight of the control be larger than would be desirable.